In vivo failure analysis of intramedullary cement restrictors in 100 hip arthroplasties

Background We occasionally noticed excessive distal plug position in our clinical routine of cemented hip arthroplasties. We therefore performed an analysis of risk factors for migration of a biodegradable intramedullary gelatine plug.

Patients and methods The performance of a cement restrictor was studied in 100 consecutive cemented total hip arthroplasties implanted with third-generation cementing techniques. In a radiographic analysis anatomical parameters, cement mantle quality, and mechanisms and factors for restrictor failure were evaluated.

Results 40 restrictors showed inadequate performance: 5 cases of tilting, 22 cement leakages, 16 excessive migrations, 2 excessive migrations plus leakages, and 1 case of leakage plus tilting. excessive migration (< 5 cm) was more common in large intramedullary canals (p = 0.04) and cement leakage was more common in patients with a proximally located isthmus (p = 0.04). Half of the hips showed a complete or almost complete filling of the intramedullary cavity, which was more often found in operations carried out by experienced surgeons.

Interpretation A more reliable plug design should be considered for patients with wide intramedullary canals and a high isthmus, to minimize the risk of plug migration and poor cement mantle quality.